Thanks to her impressive musical knowledge and her easygoing charm, Jewel has had no trouble fitting in on this season of The Sing-Off.But it seems no one has taken to Season 4's new addition more than host Nick Lachey.The best ...

In this exclusive sneak peek from Monday's season finale (8/7c, NBC), Lachey reflects on their "magical season together" before busting into a swoon-worthy performance of "It Had to Be You." And Jewel is so moved by his efforts, she takes the stage and makes it a duet!

To hear what kind words Jewel had for Lachey and his dimples, and to see their impressive dance moves, check out the heartwarming clip below:
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The Sing-Off airs Wednesday at 8/7c on NBC. The Season 4 finale airs Monday at 8/7c.